docs: def converter(val, current_unit, destination_unit):
      """Convert from one unit to another.
  
      Parameters
      ----------
      val : number
          Number to convert.
      current_unit : string
          Current unit.
      destination_unit : string
          Destination unit.
  
      Returns
      -------
      number
          Converted value.
      """
      x = val
      for dic in dicts.values():
          if current_unit in dic.keys() and destination_unit in dic.keys():
              try:
                  native = eval(dic[current_unit][0])
              except ZeroDivisionError:
                  native = np.inf
              x = native  # noqa: F841
              try:
                  out = eval(dic[destination_unit][1])
              except ZeroDivisionError:
                  out = np.inf
              return out
      # if all dictionaries fail
      if current_unit is None and destination_unit is None:
          pass
      else:
          warnings.warn(
              "conversion {0} to {1} not valid: returning input".format(
                  current_unit, destination_unit
              )
          )
      return val